Substantially, all present-day copiers, printers, plotters, etc., include a controlling microprocessor which requires input control parameters to assure high quality production of documents. Since most such apparatus allows user-replacement of consumable items, various techniques have been developed to enable entry of such parameters.
In regards to inkjet printers, it has been proposed that print heads incorporate a parameter memory for storage of operating parameters such as: drop generator driver frequency, ink pressure and drop charging values (see "Storage of Operating Parameters in Memory Integral with Print Head", Lonis, Xerox Disclosure Journal, Volume 8, No. 6, November/December 1983, page 503). U.S. Pat. No. 5,138,344 to Ujita, entitled "Inkjet Apparatus and Inkjet Cartridge Therefor", indicates that an ink-containing replaceable cartridge can be provided with an integral information device (i.e., a resistor element, magnetic medium, bar code, integrated circuit or ROM), for storage of information relating to control parameters for the inkjet printer. Murray et al. in U.S. Pat. No. 5,610,635, describe a printer ink cartridge which includes a memory for storing various parameters related to ink contained within the cartridge.
U.S. Pat. No. 5,365,312 to Hillmann et al., entitled "Arrangement for Printer Equipment Monitoring Reservoirs that Contain Printing Medium", describes the use of memory devices integral with ink reservoirs which store ink consumption data (for use by a coupled inkjet printer). European patent EP 0 720 916, entitled "Ink Supply Identification System for a Printer" describes the use of an ink supply having an integral EEPROM which is utilized to store data regarding the identity of the ink supply and its fill level.
The prior art further teaches the use of consumable parts with integral memory for use in electrophotographic printers. In U.S. Pat. No. 5,021,828 to Yamaguchi et al., entitled "Copying Apparatus having a Consumable Part", a toner cartridge is disclosed which includes a memory for storing data regarding to the state of consumption of toner in the cartridge. U.S. Pat. No. 4,961,088 to Gilliland et al.; U.S. Pat. No. 4,803,521 to Honda; U.S. Pat. No. 5,184,181 to Kurando et al.; and U.S. Pat. No. 5,272,503 to LeSueur et al. all describe various replaceable toner cartridges for use in electrophotographic printers. Each cartridge incorporates a memory device for storing parameter data regarding the cartridge.
Current inkjet printers mount inkjet printheads on a scanning carriage which is scanned across a media sheet, as the sheet is fed by the printer's sheet feed apparatus. At one extreme of the scan path is positioned a mechanism for maintaining the printhead in good working order. That mechanism is called a "service station" and is provided with both (i) rubber caps that protect the printhead's nozzles and nozzle plate during periods of non-use and (ii) a wiping mechanism for removing accumulated crust which builds up on the nozzle plate over time.
Two problems confront most printheads, i.e., ink plugs and ink crust. An ink plug is an accumulated amount of dried ink which plugs a nozzle and inhibits drop ejection. The dried ink builds up during non-firing time in both the capped and uncapped states, but more slowly in the capped state. Ink crust on the nozzle plate builds up during printing and is a layer of dried ink which accumulates as a result of an ink aerosol that settles thereon.
Ink plugs can be ejected by firing a nozzle (i.e., "spitting") into a spittoon that is typically positioned adjacent to the service station. The nozzle is repeatedly fired until the effect of the plug is eliminated. The number of firings required to dislodge an ink plug is determined by whether the printhead has been capped or uncapped; the total time since the last firing; ambient humidity and temperature; and the type of ink. As inks become faster drying and more permanent, the number of firings needed to clear a nozzle increases.
"Pulsewarming" is one way to reduce the required number of firings to clear a nozzle. Most inkjet printheads employ heater resistors to cause ejection of an ink droplet through a nozzle. Pulsewarming is the application of a low level of current to the heater resistors which is insufficient to cause ink ejection, but is sufficient to warm the ink substrate and hence the ink. The heated ink acts as a better solvent in removing ink plugs.
In the prior art, the printer firmware included parameters which controlled the number of "spits" of ink that were used to dislodge an ink plug and the current level required to achieve pulsewarming. However, because ink chemistries and printer designs are continually evolving, it is difficult to establish optimal spitting and pulsewarming criteria at the time of introduction of a printer to the marketplace. In other words, the aforesaid parameters are "moving targets"--even after a printer model is introduced.
Ink crust is normally removed by wiping the nozzle plate at the service station. With new, more permanent and fast drying inks, it has been found that more effective wiping is accomplished when a solvent (e.g., polyethylene glycol) is placed on the absorbent material that is used as the wiper. In addition, the order of spitting, wiping and cleaning can be important to the proper maintenance of the printhead.
Clearly there are a number of factors which should be considered when undertaking to control an inkjet printer's service station to assure long printhead lifetime. Among the factors are those which are directly related to the removal of ink plugs and the wiping action. Since many of those factors are variable during the lifetime of a printer, the prior art has used conservative, compromise servicing routines to achieve a best case operation. However, such compromises do not lead to best quality print documents. Also, such compromise service routines can take more time than necessary, slowing down printing operations.
Accordingly, it is an object of this invention to provide a print apparatus with an improved capability for adjustment of printer control functions.
It is another object of this invention to provide an improved printer control system which is able to update control parameters for a service station that are dependent upon current printer performance parameters.
It is yet another object of this invention to provide improved service station operation for an inkjet printer, wherein control parameters for the service station are read from plural consumable parts.
It is still another object of this invention to be able to alter the servicing routine of the printer based on new software routines contained in plural consumable parts.